1. Field of the Invention
The present invention relates to a portable air blowing working machine, and in particular, to a portable air blowing working machine (such as an air blowing cleaner which is designed to perform cleaning by collecting fallen leaves and refuse and a power sprayer which is designed to perform chemicals-spray working) which is designed to utilize an air flow (air blowing) injected from a blower which can be rotationally driven by an internal combustion engine such as an air-cooled two-stroke internal combustion engine having an air cleaner disposed in the air-intake system of the engine.
2. Description of the Related Art
FIG. 5 illustrates one example of a portable air blast cleaner representing the aforementioned portable air blowing working machine. Referring to FIG. 5, the portable air blowing cleaner 100 is of a back-pack type (see, for example, Utility Model Registration No. 2501215, pages 1–2, FIGS. 1–3) and is designed to gather fallen leaves and refuse by making use of the blowout of accelerated and pressurized air stream in place of using a broom. This portable air blowing cleaner 100 is constructed such that it comprises a back-pack frame 62 having a U-shaped configuration in plan view and provided with a couple of shouldering bands 64, a centrifugal type air blower 80 employed as an air blowing member and secured vertically through a vibration-damping member (not shown) to the back-pack frame 62, and an air-cooled two-stroke internal combustion engine 60 for rotatably driving the air blower 80, the internal combustion engine 60 being directly coupled to the rear side of the centrifugal type air blower 80 and supported by the back-pack frame 62.
The air blower 80 is constructed such that the suction port thereof (not shown in FIG. 5) is disposed to face a central portion of the back-pack frame 62 so as to enable external air to be inhaled through a space between the back-pack frame 62 and the volute case 83 thereof and that the air discharge port 85 thereof is attached to one end of the volute case 83 and extended therefrom obliquely downward so as to allow the external air that has been accelerated and pressurized to be discharged from the air blower 80. To this air discharge port 85, there are successively connected a bent pipe 91, a bellows-shaped flexible pipe 92 and an discharge pipe 95. This discharge pipe 95 is provided, at a proximal end portion thereof, with a control handle 96 furnished with a lever for operating a carburetor throttle valve of the engine 20 as well as with switches 97.
Over the top of the volute case 83 of the air blower 80, there is disposed an air cleaner 70 for cleaning the air to be introduced into the internal combustion engine 60. This air cleaner 70 is provided therein with a filter member so that the external air that has been drawn from a suction port 75 by the suction force (negative pressure) of internal combustion engine 60 can be cleaned (the removal of dust) by this filter member before the air is permitted to be introduced into the internal combustion engine 60.
Since it is generally unavoidable that the air cleaner positioned in the air intake system of the internal combustion engine is gradually clogged with dust, it is required to perform the maintenance thereof (the cleaning of the filter member, the replacement by a new filter member) at suitable intervals depending on the environments of use, operating time, etc. Namely, when the air blowing cleaner is employed in an environment where a large quantity of dust is generated, the maintenance of the air cleaner has to be performed quite frequently.
Under the circumstances, there have been conventionally proposed various measures to prolong the cycle time for performing such maintenance. For example, there is proposed a countermeasure wherein by making use of suction force (negative pressure) to be generated by the effect of the cooling fan of the internal combustion engine, an air flow passing along the outer surface of the filter member and being subsequently discharged out of the air cleaner is separately generated apart from the air flow to be introduced through the filter member into the intake port of the internal combustion engine, thereby making it possible to remove the dust clogging the filter member from the filter member (see, for example, Utility Model Registration No. 2595842, pages 1–3, FIGS. 1–6).
In the case of the portable air blowing working machine, in particular, the back-pack type air blowing cleaner illustrated above, due to the manner of operating the cleaner wherein the gathering work of fallen leaves and refuse is executed by the drifting of the fallen leaves and refuse that can be effected by the blowout of accelerated and pressurized air instead of using a broom, dust is inevitably permitted to be blown up by the effect of the blowout air and also permitted to intermingle with the air to be inhaled into the air cleaner. As a result, the clogging of the filter member may be caused to occur quite frequently, thus shortening the cycle time for the maintenance of the air cleaner and hence raising the problem that the working efficiency using the air blast cleaner is caused to deteriorate proportionally.